On a recent home inspection in Carlsbad, Ca, I came across rusted cast iron drain piping that had been painted over. Cast iron has been successfully used as plumbing material for hundreds of years up until the early 1970’s. Like everything, cast iron does eventually break down and has a typical life expectancy of approximately 50 years. Since cast iron typically corrodes from the interior outwards, an inspection by a licensed plumber with a camera is the only way to get a clear picture of the condition of the existing cast iron drain piping.
Tree roots are another factor that can undermine the integrity of the underground drainage system. Anytime you’re buying an older home with cast iron drain piping or large mature trees in the yards, a sewer camera inspection by a licensed plumber is highly recommended. The presence or lack thereof of rusk on the exterior of the cast iron piping is not a reliable indicator of the interior condition of the piping. There are times however, when rust bubbles may appear indicating the corrosion has reached the exterior of the pipe and should be replaced.
Does all this mean that you should avoid a home that has cast iron piping or that you should replace all the existing cast iron piping? In short, no. One just needs to be aware of the fact that the aging system will need repairs and replacement part of ongoing maintenance with the property. By hiring a home inspector, you can find out if your potential home has an aging cast iron system and decide how you want to approach the situation.
Here are some various pictures of aging cast iron systems that are at or are approaching the end of their useful life:
Red Rock Home Inspections is located in Vista, Ca